Wine recently enabled XInitThreads, and now all my wine applications deadlock,
including notepad (the wine version). Tracking down the problem brings me to a
call to XFilterEvent, which does not complete. The previous X call is always
XCheckIfEvent.
Interestingly enough, compiling the same version of libX11 on my computer does
not deadlock. Compiling with the extra patches and configure flags from the spec
file still does not deadlock. Compiling with rpmbuild will deadlock every single
time - I guess CFLAGS are breaking it.. FORTIFY_SOURCE, GNU_HASH and such..?
This is the 32-bit version of libX11 on amd x86_64, in case that makes any
difference... libX11-1.0.3-4.fc6, Fedora Rawhide.

Since this bugzilla report was filed, there have been several major updates,
which may have resolved this issue. Users who have experienced this problem are
encouraged to upgrade their system to the latest version of their distribution
available.
Please, if you experience this problem on the up-to-date system, let us now in
the comment for this bug, or whether the upgraded system works for you.
If you won't be able to reply in one month, I will have to close this bug as
INSUFFICIENT_DATA. Thank you.